Process of cracking hydrocarbon oils



Nov. 17, 1931. J. D. SEGUY PROCESS OF CRACKING HYDROCARBQN OILS FiledDec. 24, 1927 fianiZDeZa life 56 ga (10% fl li y,

Patented Nov. 17, 1931 UNITED srAr s PATENT" o'FFicE 'JEAN DELATTRESEGUY, OF CHICAGO, ILLINOIS, ASSIGN'OR '10 UNIVERSAL OIL PROD- UCTSCOMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA.

rnocEss or caacxme HYDROCARBON orLs Application m December 24,1927.Serial No. 242,434.

This invention relates to improvements in process of crackinghydrocarbon oils, and its novel features are more particularly directedto certain improvements in so called vapor phase cracking.

With the increasing advent of combustion engines having high compressionratios, it

has been found desirable to use motor fuels containing what are commonlyknown as anti-knock compounds. These anti-knock compounds are in someinstances increased or produced by the formation of a relatively largepercent of unsaturates in the gasoline or motor fuel. The presentinvention is adapted in its novel features to produce these anti-knockcompounds in part, at least, through" the cracking of the vapors in whatis generally known as "vapor phase cracking.

The invention is also adapted as part of a continuous process to producegasoline or gasoline like bodies, which are relatively low inunsaturates. In addition, the process can be so operated as to more orless quantitatively control the percent of unsaturates.

In this application, as will hereafter more clearly appear, I havedescribed my basic process, together with various specific exampleswhlch may be carried out utilizing the broader idea of the invention,but with modified details depending upon the results desired, or thecharacter of oil under treatment.

This process is of such a character that the raw charging stock, whethergas oil, fuel oil, crude or reduced crude, or the like, may be firstsubjected to the well known so called liquid-vapor phase cracking underpressure and certain of the gasoline constituents so formed may then, ifdesired, be removed from the system, while the reflux condensate from,

such pressure cracking'may then be subjected to vapor phase cracking, oratmospheric, or reduced pressures.

By such operation the reflux condensate so formed is preferably,separated from the carbon containing residues, and becomes a relativelyclean charging stock for the vapor phase cracking operation. 1

At he same time, if desired, the residue produced from the liquid-vaporphase pressure operation may be flashed and the flashed desirable andrelatively clean char mg stock for the vapor phase operations. T eprocess may beso carried out that the reflux from the main pressurecracking operation may be independently treated from the vapors producedby the flashing of the residuum, or they may be treated together, as acommon vapor phase cracking stock.

Another feature of this invention is that the hydrocarbon which aresubjected to the vapor phase crac ing, have prior thereto, already beenso treated by the pressure process as to'more or less crack them,whereby the subsequent cracking of such reflux or vapors in the vaporphase part of the process, is much easier than would be the case werethe raw charging; stockinitially subjected to straight vapor p asecracking.

It is well known in present vapor phase cracking that the fuelconsumption is high and the incondensible gas loss is large. Inaddition, in present types of vapor phase cracking the carbon productionis high.

cracking conditions.

It is to be understood that by means of the present process the oil isso preliminarily y means of the present invention the fuel contreatedprior to the vapor phase operation that it is in prime condition forvapor phase cracking, because it has already been initially crackedwith. the formation of some unsaturates and the vapor phase part of theopera tion in realit com letesv the maximum for mation of antl-knoccompounds already previously started.

Heretofore vapor phase processes have only the present invention heavyfuel oils or crude petroleum may be cracked to obtain the maximum amountof gasoline, and certain of the constituents thereof converted into amaximum amount of anti-knock compounds.

Another feature of the invention is that the reflux produced from thevapor phase cracking, may, if desired, be mixed with the raw chargingstock in the pressure part of the process, and lnasmuch as the refluxcontains in itself a large amount of anti-knock compounds the gasolinefrom the pressure part of the process will in such case be produced witha large amount of anti-knock compounds.

I have above referred to a certain part of the process as liquid-vaporpressure opera; tion and another part as vapor phase cracking atatmospheric pressure. It is to be understood, however, that in itsbroader aspect the invention is not limited to the vapor phase crackingat atmospheric pressure,

as good results -may be obtained even though the vapor phase crackingpart of the operation is carried out at superatmospheric pressure or atsubatmospheric pressure. For example, the liquid-vapor pressure /part ofthe process may be at say 100 lbs. upwards and the vapor phase crackingat pressures of lbs. or lower.

It is to be understood that these figures are merely illustrative and inno sense intended to limit the scope of invention on the degree ofpressure.

The invention will be more clearly understood from the followingdescription, reference being, had to the accompanying draw- This drawingshows a diagrammatic illustration of an apparatus and in my opinion anovel form of apparatus suitable for carrying out the invention. It isto be understood that this diagrammatic drawing is not to scale or 1intended to be. N Referring to the drawing, a cracking coil 1 ispositioned in a suitable furnace 2. Raw

oil is supplied to the coil 1 through feed line.

' after described.

of the dephlegmatormay be controlled either by introducing raw oildirectly into the vapors in the dephlegmator through pipe 18, havingcontrol valve 19, or in the event it is undesirable to introduce the rawoil directly to the dephlegmator, as is true in certain caseshereinafter described, then the raw oil may be fed through a closed coil20, which closed coil may, if desired, lead the oil in its passagethereto, to the pump 4.

The reflux condensate from the dephlegmator 9 is drawn olf through thelower end thereof through pipe 21, and thence may be returned throughlines 21 and 22 and pump 23 to the raw oil feed line 3. A by-pass 24 maybe provided in line 22 around the pump 23, suitable valves 25 beingprovided as shown.

In the line 21, is provided a throttle valve 26. The reflux may. also bepassed through line 27 and branch 28 to vapor phase feed line 29,hereinafter referred to.

A pump 30 may be interposed in line 27, and a by-pass line 31 around thepump may also be provided, throttle valves 32 beinginterposed as shownin the drawing.

The reflux condensate may instead of being sent through branch 28, afterit reaches 27, be diverted through pipe 33, having throttle valve 34,and then combined with the residuum drawn off from' chamber 7 by meansof draw-ofi' line '35 and branch 36, the latter leading to the residuumflash chamber 37. A valve 38is interposed in the line 36 and a throttlevalve 39 is interposed in an extension of the line 35, below thejuncture of theline 35 with the line 36, whereby some of the re-' siduummay be drawn entirely out of the system, if desired. 2

The vapors which are flashed from the flash chamber 37 pass out throughthe upper part thereof through pipe 40, having throttle valve 41 andthence to the line 29. At the lower end of the flash chamber 37 is, aresiduum draw bfl' 42 having throttle control valve 43.

In certain cases the flash chamber 37 may be by-passed and the chamber 7used as a combined reaction 'or expansion and flash chamber. In suchcases all of the vapors from chamber 7 may either pass to thedephlegmator 9, or they may pass directly to line 29 by means of abranch pipe 44, having throttle-valve 45.

A throttle valve 46 may be interposed in line 8 as well as Valve 47-A inline 29, for a purpose hereinafter described. This line 29 leads to thevapor phase cracking coil 47, seated in a suitable furnace 48. Theoutlet end of the coil connects through delivery line 49 having throttlevalve 50, into chamber 51. This separating chamber 51 is provided with acarbon or'residue draw off pipe 52, having throttle valve 53, and withvapor outlet pipe 54, having throttle valve 55. The pipe 54 leads to theside of dephlegmator 56. The temperature in this dephlegmator may be controlled either by introducing raw oil directly e such a character thatit is so clean a charging stock that it can be passed directly to thevapor phase cracking coil 47, without materially increasing carbonformation in the vapor phase coil.

The vapors pass out of dephlegmator 56 through vapor line to condensercoil 61 and thence to receiver 62, which is provided with gas outletcontrol valve 63 and liquid outlet control valve 64. If desired thevapors from dephlegmator 9 may also pass into receiver 62, thuseliminating receiver 15. To this end a vapor pipe having control valve66 may lead from the line 12 to the. line 60. v

The reflux condensate from dephlegmator 56 passes out of the lowerend.through pipe 67, and thence through pump 68 to line 69. The by-pass7 0 may be provided around the pump with the usual valves 71. The refluxfrom line 69 may be passed directly, if desired, to line 29, by means ofpipe 72, having throttle valve 73 and line 28, or if desired it may passvia line 72 into line 33 by opening the'valve 34 and closing the valve74 in the line 28, or the condensate may be passed from thepipe 69 intothe line 22 by closing the valve 73 and opening the valve 7 5. Thereflux from either dephlegniator may be drawn out of the system-throughbranch 77 having throttle valve 78, or branch 79, having throttle valve80. i

Describing no w the manner in which the invention may be operated, onedesirable method of carrying out the invention is to subject the rawcharging stock to a liquid vapor phase pressure cracking operation,

flash the residuum therefrom and subject the flashed vapors tovaporphase cracking at atmospheric pressure or pressure'lower than the mainpressure, and to also subject the reflux condensate from. the maindephlegmator to vapor phase cracking. In such case, the raw oil, ifdesired, may be passed through the dephlegmator connecting thevaporphase cracking coil, either in direct or indirect contact with thevapors in such dephlegmator and thence to the main cracking coil. The

reflux from the second dephlegmator or the dephlegmator connected to thevapor phase cracking coil, is or may be returned to the main highpressure cracking coil.

. Describing the above method of carrying out the invention more indetail, the raw oil is fed into the coil 1 where it may be heated to atransfer temperature of say 750 F. to 900 F. more or less and thenceinto the expansion chamber 7. The vapors pass out of expansion chamber 7through line 8 into main dephlegmator 9. Here the heavier portions arecondensed while the lighter vapors pass out through line'12, either intoreceiver 15 or receiver 62 by suitably regulating the valves shown inthe accompanying drawing. The reflux condensate may be drawn out throughpipe 21 and thence if desired pass,

through pipes 31, 27 and 28 into the line 29, and thence to the vaporphase cracking coil 47. If desired, the reflux condensate instead ofpassing, to pipe 28 may go from pipe 27,

via the pipe 33, to the line 36. The residuum is drawn off the bottom ofchamber 7 continuously and thence may be passed through the pressurereducing valve 38, and be flashed into chamber 37. The vapors from suchflashing operation thence pass throu h the pipe 29 into the vapor phasecoil 47. pressure of 100 lbs. upwards may be maintained in coil .1,chamber 7, dephlegmator 9 and on receiver'15, by suitably regulating thevalves 16 and 17 on receiver 15 and valves 32 and the reducing valve 38.If desired the valves 74 and 34 may be used as reducing valves dependingupon whether the line 28 or 33 is P atmospheric, say 20 to 50 lbs. moreor less.

If desired, the vapor phasecracking coil may be even maintained under avacuum, by con-.

necting suitable vacuum pump not shown to the receiver 62. In such casethe pump 68 may be used as a double action pump. vacuum on the inlet andpressure on the discharge side. The contents of vapor phase coil 47 arethen preferably passed to chamber 51 where any carbon containingportions may be dropped out and be drawn out of the system, while thebalance goes through the line 54 to dephlegmator 56. In thisdephlegmator 56 the heavier portion will be condensed. and may then bepassed through the lines 67 and 69 directly back to the main heatingcoil 1. In such case the valves 26 and 73 are closed and the refluxcondensate from-dephlegrnator 56 may then readily pass directly to coil1' The portion of the oil which is passed through the vapor phasecracking coil is converted into a relatively large percent ofunsaturated aromatics or other anti-knockcompounds, and may then, ifdesired, be blended with straight run gasoline or with gasolineprocharging stock used may, as heretofore stated, .be either gas oil,heavy fuel oil or crude, and it may be noted that by the presentinvention I not only crack such heavier oils but in doing so separateout therefrom highly desirable clean charging stock already partiallycracked, which is very suitable for the vapor phase operations 1 At thesame time it will be noted that the charging stock which goes to thevapor phase cracking coil has not only been partially cracked asheretofore stated, but it thus necessitates a minimum amount ofadditional fuel for the vapor cracking coil. 2 Furthermore, inasmuch asthe portion of the oil which passes throughthe vapor phase cracking coilhas already been more or less cracked lower temperatures may be used inthe vapor phase coil, thus materially lessening the objectionable highgas losses incident to heretofore known vapor phase cracking processes..It will be further noted that by this process the gasoline produced bythe pressure operation of the process is removed and not subjected tothe vapor phase cracking. In addition. if the reflux condensate from thevapor phase cracking operation is returned to the main cracking coilthen the gasoline formed by the pressure part of the process will havemixed with it a certain amount of desirable anti-knock compounds.

Another important feature of this manner of carrying out the inventionis that the rate and extent of cracking in the pressure part of theprocess may-be regulated entirelv independently of the vapor phase partof the cracking, and also'the reverse is true. While I have stated thatby this process the vapor phase cracking can be carried out at a lowertemperature than in certain heretofore known processes, it is to beunderstood that I. in no sense limit myself to such temperaturesrelative to prior processes, because it may be desirable to subject theoil passing through the vapor phase cracking coil to very hightemperatures, and while this, of course, will-not tend to lessen the gaslosses, nevertheless the process will still have the advantages of a lowfuel consumption and a highly desirable charging stock.

Certain features disclosed but not. specifically claimed herein comprisethe claimed subject matter of my copending applications Serial Nos.242,435, 242 436, and 242,438, filed on even date herewith. I e

I claim as my invention 9 1 1. A process for cracking hydrocarbon oil,which comprises passing the oil through a heating coil and .thence intoan expansion chamber under pressure, taking off vapors from saidexpansion chamber and subjecting them to reflux condensation to formreflux condensate, withdrawing the residuum from said chambeg and flashdistilling it at reduce-d pressure, then subjecting the vapors from andpressure in an initial cracking zone, sepvapor phase cracking.

said flash distillation and said reflux condensate to vapor phasecracking, removing the vapors from said vapor phase cracking step;subjecting them to reflux condensing action and returning said reflux tothe main heating coil for further cracking.

2; In a hydrocarbon'oil cracking process, the improvement whichcomprises subjecting the oil to cracking conditions of temperaturearatlng the evolved vapors from the unvaporized oil, removing saidunvaporized oil and reducing the pressure thereon, thereby formingadditional vapors, and subjecting said additional vapors to vapor phasecracking in a vapor phase cracking zone, dephlegmating the vapor phasecracked vapors thereby forming reflux condensate, and returning oneportion of said reflux condensate to said initial cracking zone andanother portion thereof to said vapor phase cracking zone.

3. In a hydrocarbon oil cracking process, the improvement whichcomprises subjecting the oil to cracking conditions of temperature andpressure in an initial cracking zone, separating the evolved vapors fromthe unvaporized oil, removing said unvaporized oil and reducing thepressure thereon, thereby forming additional vapors, and subjecting saidadditional vapors to vapor phase cracking in a vapor phase crackingzone, dephleg mating the vapor phase cracked vapors there by formingreflux condensate, and returning reflux condensate to said initialcracking zone. a 4. In a hydrocarbon oil cracking process, theimprovement which comprises subjecting the oil to cracking conditions oftemperature and pressure in an initial cracking zone, separatelyremoving the evolved vapors and un- 1 vaporized oil, dephlegmating theevolved vafiux condensate to effect vaporization thereof, reduclng thepressure on sald unvaporized oil to formadditional vapors, andsubjecting said additional vaporsand the vapors formed by reductionofpressure on the reflux condensate to vapor phase cracking,dephlegmating the vapor phase cracked vapors, thereby forming additionalreflux condensate, and returning one portion of said additional refluxcondensate to said initial cracking zone and another portion thereof tothe 5. In a hydrocarbon oil cracking process,, l the improvement whichcomprises subjecting the oil to cracking conditions of temperature andpressure in an initial cracking zone, separately removing theevolvedvapors and unvaporized oil', dephlegmating the evolved vapors underpressure, thereby forming reflux condensate, reducing the pressure onsaid reflux condensate to effect vaporization thereof, reducing thepressure on said unvaporized l oil to form additional vapors,andsubjecting said additional vapors and the vapors formed by reductionof pressure on the reflux condensate to vapor phase cracking,dephlegmating the'vapor phase cracked vapors to condense insuflicientlycracked fractions,and returning at least a portion of the condensedinsuificiently cracked fractions, to said initial cracking zone.

6. In a hydrocarbon oil cracking process, the improvefnent whichcomprises subjecting the oil to cracking conditions of temperature andpressure inan initial cracking zone, sep

arately removin the evolved vapors and unvaporized oil, ephlegrnatingthe evolved vapors under pressure, thereby forming reflux condensate,reducing; the pressure on said reflux condensate to efi'ect vaporizationthereof, reducing the pressure on said unvaporized oil to formadditional vapors, and

subjecting said additional vaporsand the va I tions, and returning atleast a portion of the pors formed by reduction of pressure on thereflux condensate to vapor phase cracking, dephlegmating the vapor phasecracked va pors to condense insufliciently crack ed fraccondensedinsufliciently cracked fractions to the vapor gl'ase cracking.

AN DELATTRE SEGUY.

